We are conducting a wine tasting and dinner to raise money for research for ALS (Lou Gehrig's disease). People are also donating bottles of wine for auction. We have been given a magnum of 1874 Lafitte Rothchild from the cellar of the Duke of Braanespath. The wine was bought at a Sotheby auction some years ago. The bottle (hand blown) has the Duke's seal embossed in the glass. The lead foil is mostly gone, but has the top which is stamped 1874. The wine has evaporated under the neck, but is still mostly full. Do you have any idea as to what it may be worth?